Lithium in drinking water ‘may reduce suicide’

Embargoed until 28 April 2009

Very low levels of lithium in drinking water
may help prevent suicide in the general population, according to a
new study.

The
study has prompted calls for further research into the
possibility of adding lithium to drinking supplies – like water
fluoridation to improve dental health. Researchers at Oita
University in Japan measured lithium levels in tap water in 18
municipalities in the Oita region. The lithium levels ranged
between 0.7µg/l (micrograms per litre) and 59µg/l.

The researchers then calculated the suicide
rate in each of the 18 municipalities. They found that the suicide
rate was significantly lower in those areas with the highest levels
of lithium in the water.

Writing in the May issue of the British
Journal of Psychiatry, the researchers said: “Our study
suggests that very low levels of lithium in drinking water can
lower the risk of suicide. Very low levels may possess an
antisuicidal effect.”

Lithium is a naturally occurring metal found
in variable amounts in food and water. In medicine, very high doses
are used to treat bipolar disorder and mood disorders. But so far
the potential benefit of using low levels of lithium to reduce the
risk of suicide has not been studied closely.

Vancouver-based psychiatrist Professor Allan
Young has described the study as “intriguing”. Commenting
on the Japanese study in the same issue of the British
Journal of Psychiatry, Professor Young said: “A logical first
step would be for the Medical Research Council to convene an expert
working party to examine the available evidence and suggest further
research.

“Large-scale trials involving the addition of
lithium to drinking water supplies may then be feasible, although
this would undoubtedly be subject to considerable debate. Following
up on these findings will not be straightforward or inexpensive,
but the eventual benefits for community mental health may be
considerable.”